Roller dryer



5121216 10, 1969 R. HILDEBRAND 3,448,524

ROLLER DRYER Filed Dec. 19, 1967 Sheet of 2 FIG I.

INVENTOR. BY ROBERT HlLDE-BRAND ATT Y5,

June 10, 1969 R HlLDEBRAND 3,448,524

ROLLER DRYER Filed Dec. 19, 1967 Sheet 2 01% FIG] FIG. 8.

INVENTQR'. ROBERT HILDEBR AND ATTYS.

United States Patent U.S. Cl. 34-149 Claims ABSTRACT OF THE DISCLOSURE A multi-deck roller dryer for sheets of material in which the driven rollers are horizontally-spaced in roller planes and nozzle boxes are disposed between the rollers in each plane. The material is convey-ed in each deck by the roller plane underlying the sheets and is pressed against the undersides of the rollers in the upwardly adjacent plane whereby n+2 roller planes form n+1 decks. The nozzle boxes have slits forming the nozzles for effecting contact of the drying medium with the sheets, the slits being disposed at an angle of between 30 and 60 to the direction of travel of the material. Deflector plates are provided for the nozzle slits which are graduated in length with the longest plates furtherest from the medium inlet to the box.

The invention concerns a roller dryer for drying panellike material, in particular veneer sheets, in which there are a number of superposed decks and means for circulating the drying medium in contact with the material in the decks.

With known roller dryers, the material that is to be dried is conducted between pairs of roller planes in sequence, so that for example, for three superposed decks or paths, there have to be three superposed pairs of roller planes. The drying medium is directed either countercurrent or concurrent to the direction of travel of the material, or else transversely to that direction, over the material. The known roller dryers therefore are very tall structures.

By means of the invention, it is intended to obtain a diminution of the height of roller dryers, while retaining the drying action inside the dryer, this being possible according to the invention in that 2+n superposed roller planes provide at least 1+1: (n=1, 2, 3 decks or paths for conveying the material that is to be dried. Each roller plane has a series of horizontally-spaced rollers, and in the spaces between the rollers, nozzle-boxes are provided with nozzles directed toward the material to be dried. At each end of the dryer, means is provided for reversing the material to be dried. The nozzle-box may be constructed either as a blowing box or as a suction box. A substantial saving of space is obtained in that each roller in the intermediate roller planes is used for conveyance in both directions, thereby reducing the number of roller planes needed in comparison with known roller dryers. The lower or supporting rollers of the upper deck are at the same time the upper or pressure rollers of the deck directly below. Each deck thus uses only one roller plane, as against two roller planes in other cases, which makes possible a compact form of construction. By means of the direct impingement of the material to be dried, by the aid of the nozzle-boxes made to match the diameter of the rollers, the drying medium is brought directly to the material that is to be dried, through which there is avoided any poor impingement of the material to be dried because of the small spacings existing between the paths for the material.

In a further development of the invention, the height of the nozzle-box is at the most, and is in particular, somewhat smaller than, the diameter of a roller; and the slit-nozzles of the nozzle-box, at its side turned toward the material to be dried, run at a slant relative to the roller axis, and extend almost 'across the breadth of the box between the rollers on opposite sides thereof. Be cause of this, it is possible to obtain good impingement of the material to be dried, in spite of the small overall height of the nozzle-box.

It is moreover possible to obtain an improvement of the impingement against the material by [forming the slitnozzles with guide plates or deflectors projecting substantially perpendicular inward from the wall confronting the material to cause the drying medium to impinge against the material perpendicularly.

The drawings show schematically a roller-dryer in one example of construction of the object of the invention, its other characteristics being given by the specification in association with the claims.

FIG. 1 is a longitudinal section through a dryer embodying the present invention;

FIG. 2 is a cross section taken along line 2-2 of FIG. 1;

FIG. 3 is an enlarged fragmentary sectional view of the dryer shown in FIG. 1 showing the blowing of the drying medium against the material;

FIG. 4 is an enlarged cross section taken along line 4-4 of FIG. 3; I

FIG. 5 is an enlarged section taken along line 55 of FIG. 3;

FIG. 6 is a perspective view of the arrangement of FIG. 5;

FIGS. 7 and 8 are views corresponding to FIGS. 3 and 4, showing the sucking of the drying medium away from the material;

FIG. 9 shows an enlarged section through bearings for the rollers, taken along line 9-9 of FIG. 7;

FIG. 10 shows an enlarged section through ends of nozzle boxes along line 1010 of FIG. 3; and

FIG. 11 is a fragmentary longitudinal section through another embodiment of a dryer in accordance with the present invention.

Referring to the roller dryer shown in FIGS. 1-10 inclusive, there is a drying chamber 1 having disposed above it, air-supplying channels 2 at one side of which are disposed a plurality of blowers 3 and at the other side of which are disposed heat exchangers or heating registers 4 (see FIG. 2). Inside the drying chamber 11, driven conveyor rollers 5 are disposed in a plurality of roller planes wherein the rollers are horizontally spaced to accommodate nozzle boxes 6 therebetween which effect contact of drying medium directly with the material conveyed between the roller planes.

The rollers in the first or uppermost plane are driven counterclockwise whereas the rollers in the second plane are driven clockwise. The drive of the rollers in the successive planes alternates between clockwise and counterclockwise, the odd-numbered planes being driven counterclockwise and the even-numbered planes being driven clockwise. The lowermost plane, being the twelfth plane, is driven clockwise. Thus, a first deck is provided between the first two planes of rollers, a second deck is provided between the second and third planes of rollers and so forth, whereby the twelve roller planes provide an elevendeck dryer. The roller dryer in accordance with the present invention may have any desired number of decks or conveyance paths, in the present instance there being eleven. -In any event, it is preferred that the number of decks be odd, in order that the entrance end of the dryer may be opposite to the exit end. In this case, the material is introduced into the drying chamber 1 at the upper left hand corner as shown in FIG. 1, as indicated by the arrow A to pass between the first and second roller planes and is discharged from the drying chamber 1 at the lower right hand corner as indicated by the arrow B between the eleventh and twelfth roller planes.

, Means is provided at the opposite ends of the drying chamber to receive the panels of material from one deck and to feed the same into the next deck. In the present instance, a reversing device 7 is provided at the left hand end of the dryer as shown in FIG. 1 and a reversing device 8 is provided at the right hand end of the dryer. The reversing device 7 operates upon discharge of the material panels from between the even and odd-numbered roller planes to direct the panels in the reverse direction between the same odd-numbered plane and the next evennumbered roller plane. Rollers coplanar with the evennumbered planes are provided which may be either idle or may be positively driven as desired. In the illustrated embodiment, the rollers are clutched to be idle so as to be driven by the sheet as it travels from the preceding deck until the sheet contacts the stop, and then are driven to convey the sheet into the next deck. At the other end, the reversing means 8 includes rollers coplanar with the oddnumbered roller planes so as to receive the panels of material from one deck between the odd-numbered and evennumbered planes and direct the material panels into the next deck between the same even-numbered roller plane and the next odd-numbered roller plane.

The height of the nozzle-boxes 6 situated between the rollers 5 is somewhat smaller than the diameter of the rollers, which amounts to about 100 mm. (about 4 inches). The nozzle-boxes 6 have, at the side of them turned toward the material to be dried, slit-nozzles 9, which are in particular set at an angle between and 60 to the direction of travel of the material and adjoin one another without excessive overlapping. Inside the nozzle-boxes 6, and at their sides turned away from the direction in which the drying medium is conveyed, are provided upstanding deflectors or guideplates 10, which in the region of the entry side 11 of the nozzle-boxes 6, are shorter than at the closed sides of the boxes. The guide plates may be left standing after the stamping-out of the slit-nozzles, and may consist of bent-out parts of the nozzle-box, or else they may be separate elements attached in a suitable way to the nozzle-box.

At the sides facing the rollers 5, it is possible to conform the nozzle-boxes 6 to the rollers as shown in FIGS. 3 and 7, or one or both sides may be made flat.

The nozzle-boxes 6 extend between the pressure and suction sides of the chamber 1, as determined by the fan arrangement. In the embodiment shown in FIGS. 1 to 4, they are open to fan pressure at one side 11 to receive the drying medium blown by the fans 3 through the heat exchangers 4, and are closed at the other side so that the drying medium is exhausted to the intake of the fan 3 from between the nozzle-boxes, as best shown in FIGS. 3 and 4. Alternatively, the nozzle-boxes may be reversed so that their open sides confront the fan suction and their closed sides confront the fan pressure whereby the nozzleboxes suck the drying medium from therebetween. When drying sheets of veneer, in particular, it is preferred to blow the drying medium thereagainst, whereas with other materials, it may be desired to suck the drying medium therefrom.

As shown in FIG. 11, the reversing means 7 and 8 may have plates, in particular metal sheets 17, whose top sides are situated in the same plane as the upper crests of the corresponding rollers, instead of the outermost three or four rollers.

In the case of a roller-dryer for the drying of only one sheet thickness, the rollers are in each case mounted in stationary bearings with little clearance in the vertical direction, in order that the sheet of material may be loaded only by the actual weight of the conveyor rollers resting on it. However, if it is desired to dry with the roller-dryer a variety of sheets of different thicknesses in individual cases, then the conveyor roller 5 and the nozzle-boxes 6 must in each of these cases be adjusted to a suitable height. T 0 do this, there serves the arrangement shown in FIGS. 9 and 10.

With the arrangement of FIGS. 9 and 10, there is provided for each horizontal row a bearing frame 15, in which are fastened alternatively the conveyor rollers 5 and the nozzle-boxes 6. Each of the conveyor rollers is installed with play or clearance 16, in order that during the passage of a sheet of material, within the limits determined by the bearing play, the upper roller can become raised, and the sheet to be dried is thus loaded only by the weight of the upper rollers resting on it.

Between the superposed bearing frames 15 are provided lifting elements 12, substantially elliptical in cross section, and mounted in suitable bearings which are in each case provided with a lever 13a, 13b or 130, by the aid of which they can be turned. The levers are, seen from below or from above, progressively longer, and to each vertical row, is articulated a rod 14.

In FIGS. 9 and 10, the conveyor rollers 5 and the nozzle-boxes 6 are disposed in strata designed for the passage of the thinnest sheet of material to be dried. If a thicker sheet is to be dried, then the rods 14 are raised or lowered suitably, and thus the levers 13a to are correspondingly turned, through which the vertical intervals between the bearing frames 11 become suitably adjusted by the turned positions of the lifting elements 12. Because of the unequal lengths of the levers 13a to 130, the conveyor rollers 5 and the nozzle-boxes 6 of the uppermost row become raised more than those of the nextlower row, while the lowermost row remains at an unaltered height. The displacement of the individual bearing frames in each case corresponds to the change of thickness of the sheet of material to be dried, whereby in the case of the uppermost row, the thicknesses of those sheets are added together to correspond with the number of superposed horizontal rows or hearing frames 15'. During one oepartion, the sheets to be dried are all of the same thickness. If in a subsequent operation sheets of another thickness are to be dried, then the altitudes of the conveyor rollers 5 and of the nozzle-boxes 6 must be altered to correspond.

While particular embodiments of the present invention have been illustrated and described herein, it is not intended to limit the invention to such disclosure, but changes and modifications may be made therein and thereto within the scope of the following claims.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A roller dryer for drying sheet-like material comprising a plurality of conveyor rollers disposed in superposed roller planes, and means for circulating drying medium in contact with the material conveyed by said rollers in each plane, the rollers in each plane being disposed in horizontally-spaced parallel arrangement, the improvement where: 2+n superposed roller planes form at least 1+n conveyance paths for the material to be dried, it being an integral member,

said circulating means including nozzle-boxes disposed between the horizontally-spaced rollers in each plane said nozzle-boxes having nozzle means directed toward the material in the adjacent conveyance path, and including means for reversing the material at the opposite ends of each roller plane so that the material is caused to travel in one direction in a conveyance path on one side of a selected roller plane and immediately thereafter is caused to travel in the opposite direction in a conveyance path on the other side of said selected roller plane.

2. A roller dryer in accordance with claim 1, characterized in that the height of the nozzle-box is equal to, and is in particular, somewhat smaller than, the diameter of said rollers, and in that the nozzle means of the nozzlebox comprise slits which run at a slant relatively to the roller axis, and extend substantially the entire distance between the rollers on opposite sides thereof.

3. A roller dryer in accordance with claim 2 characterized in that the silts are formed in one wall of the nozzle-box which is provided with deflectors for guiding the drying medium through said nozzles, said deflectors being disposed interiorly of the nozzle-box and substantially perpendicularly to said one wall.

4. A roller dryer in accordance with claim 3, characterized in that the deflectors are of graduated length, being longer than at the side where the drying medium enters.

5. A roller dryer in accordance with claim 1, characterized in that nozzle means comprise slits set at an angle between 30 and 60 relatively to the axes of the rollers, and in that, looking in the direction of travel of the material, the nozzles of a nozzle-box adjoin one another laterally without excessive overlapping.

6. A roller dryer in accordance with claim 1, characterized in that the rollers and the nozzle-boxes in each plane are disposed in a common bearing frame including means to adjust the frame vertically to vary the spacing between the planes to suit the thickness of the sheet of material to be dried.

7. A roller dryer in accordance with claim 6, characterized in that the rollers are disposed in the bearing frame with such play or clearance that upon adjustment, the upper rollers forming the conveyance path rest only 6 by their own weight upon the sheet of material to be dried.

'8. A roller dryer in accordance with claim 6 or 7, characterized in that the adjusting means comprises adjusting elements of elliptical cross section and levers of differing length having an adjusting rod associated therewith to rotate the elements.

9. A roller dryer in accordance with claim 1 characterized in that the reversing means for each conveyance path comprise clutched rollers for receiving a sheet out of the path above while idle so as to be driven by that sheet, and then, for the purpose of conveying the sheet into the next path, are positively driven in the contrary direction.

10. A roller dryer in accordance with claim 1, characterized in that the reversing means comprise plates adjacent the outside of the chamber, and conveyor rollers adjacent the middle of the roller-dryer.

References Cited UNITED STATES PATENTS 2,284,838 6/1942 Oholm 34-205 XR 3,334,421 8/1967 Morris 34-205 1,037,075 8/ 1912 Spurrier 34-149 KENNETH W. SPRAGUE, Primary Examiner.

US. Cl. X.R. 34205 

